I have a 2010 Dodge Ram 2500 6.7L 6 speed trans all stock.  I got a code p0191 for fuel performance code I cleared it and it takes weeks to a month if it comes on again. It only came on twice and has been off for weeks now truck runs great ehat should fuel rail pressure be at an idle. Could idling a long time cause this using remote start a lot I doubt it could but looking for ideas and are most people fixing this code with software updates the sensor is expensive and if it ran rough or something it would be easier to track down . Thanks 

Looking over my books P0191 is "Fuel Rail Pressure Sensor Performance Circuit". Basically, there is 2 things that can fail. Either the rail pressure sensor is not working correctly or the injectors have excessive return volume and CP3 is having trouble building rail pressure because injector issues might be coming on. Being common rail injector failures are rather "common" I would like to ask how much mielage do you have on the truck. If you have 100k or 150k miles or more then I highly suggest you pull all 6 injectors have then bench tested. If any fail then replace all 6 injectors. Because the other 5 will fail soon after. 

Thanks for the info there are 108k miles on the truck and it idles and runs great. I read some stuff about bad connections at the frp sensor I'm going to put some die electric gel on the pins and inspect that. Do you know what the frp reading and voltage reading is supposed to be at idle I think that's where the code would set. I'm hoping it would be a sensor then I injectors the cost between the two is a big one. Thanks 

Give me some time I'll pull that article when I get home tomorrow.

I have the exact same problem.  I changed the fuel rail as a whole thinking it was the sensor. Still have the same problem so, now I have a good spare parts.  I’m now getting ready to do a fuel return test.  I’m just wondering if you got yours fixed and what was the problem ?  I have the answer to your last question but, I think you might have the answer already since it’s been a year and a half. 

What ended up happening?

 

I’m working on doing it.  It’s been really cold here for the last month.  I’m thinking Monday I might get out there and do it. It’s supposed to go up to -12 and be sunny.  I will definitely keep everyone on here updated even though it seems like not much happens here. 

I'm having same exact issues with my 2012 3500. Replaced the fuel rail including relief valve and pressure sensor. Still occurs only at idle at long stop lights. I run good fuel replace my fuel filter every 6,000 miles when I do the oil. I have 137,000 miles. It's been occuring in and off the last year and half. Truck runs great otherwise. Thinking about replacing the CP3 first then the injectors. Or should I do it the other way around? I have to get this resolved before March that's when smog inspection is due. I live in California sooo any input would be appreciated 

Just wondering if anybody has updates on this ?   I did my return flow test and it was well within spec.  I still have the same problem.  Code comes up right away after 2 key cycles after being cleared.